Process of making and casting alloys.



J. F. MONN OT. PROGESS OF MAKING AND CASTING ALLOYS.

APPLICATION FILED JULY 16, 1908.

Patented Dec. 28, 1909.

. ing Alloys; and

UNITED STATES PATENT. onrion.

JOHN F. MONNOT, OF

NEW YORK, N. Y., ASSIGNOR TO MONNO'I. METALLURGICAL COM:-

PANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK;

PROCESS OF MAKING AND CASTING ALLOY S.-'

Specification of Letters fatent.

malted neazs, 1909.

Application filed July 16, 1908. Serial No. 443,?95.

To all whom it may concern:

Be it known that I, JOHN F. MoN Nor, a citizen of the United States,residing at Ne York, in the county of New York and one .or more of theconstituent metals is sealing molten readilyvolatilizable or oxidizable,and of casting such metallic mixtures or alloys.

According to my invention, the alloy to be cast is formed, or elsebrought to a molten condition, under the protection of a deep operatingboth to exclude air volatiliza-tion, and-is drawn off from a pointbeneath such layer and passed into and through a substantial or deeplayer of molten 'flux or slag contained in a suitable mold,

such tapping operation being preferably so conducted as to prevent orminimize any intermediate contact with air.

In many metallic mixtures and alloys where precise composition is ofgreat importance, as in the various brasses, bronzes, alloy steels,etc., under the present practice it is a matter of somedifiiculty tomaintain this precise composition during long treatments or duringremelting since volatilizable or oxidizable components tend todisappear. In brass, for instance, since the boiling point of zinc iscomparatively low, being about the melting point of copper, in making,melting, casting, and remelting brass, there is a steady loss of zincwhich tends to volatilize from exposed surfaces of the melted metal and,since zinc vapors are readily infiammable,to burn out. In handling brassin the melted state steadyloss of zinc and the composition of the alloysteadily varies. As fairly precise ratios between the copper and thezinc are desirable are often necessary in making alloys for specialpurposes, this represents a grave inconveniencein the art, and theprinclpal method of obviating 'it now in use is layer of floating fluxor slag and to prevent.

'zinc vapor and air cannot coexist.

there. is, therefore, a-

to add more zinc from time: to time as the zmc burns out, or to use anexcess of zinc. in. making the brass or other alloy, These-y methods areobviously disadvantageous,

Similar difficulties are met with in. handling on other alloys. The tinof bronze, though not very volatile at bronze-casting temperatures, isvery oxidizable, and burns out, not

only changing the composition of the alloy.

but injuring itby leaving infusi-ble particles of oxid. Nickel, cobalt,lead, iron and other metals also tend to burn out of copper alloys. Inthe manufacture of the modernalloy steels, the alloying bodies, such asvanadium, y, titanium, chromium, etc., are generally more oxidizablethan the iron and readily burn out, and, from their usual smallquantity, any such loss seriously afiects the quali-= ties of the alloy.In' casting these mixed metals, the stream of molten metal passingthrough or in contact with the air, in addition to taking up orentrai-ning more or less air by occlusion or adsorption, tends tooxidize, becoming covered withoxid pellicl'es which prevent good contactwith the moldand accurate shaping. Intthe case of brass and otherzinc-alloys, the loss of zinc in casting is quite serious.- Intheevaporation of any liquid, such as the zinc from the molten alloy, theamount evaporated in a time unit-1s directly proportional to the surfaceexposed and inversely proportional to the amount of its vapor alreadypresentin the space into which evaporation proceeds As the melting-pointof brass is not far'be low the boiling point ofzinc, so that the tensionof zinc vapor from molten brass is quite large, it follows that,irrespective of the oxidizing effect of air, the conditions for the lossof zinc are nearly ideal in pouring a thin stream of molten brassthrough free" air into a mold, a maximum surface of hightemperaturemetal being exposed to an atmosphere which is free of zinc vapors, sincemore, apart from changes in composition, of the alloys incident tomelting and pouring-,- in pouring much air is generally carried for.-ward by entrainment, and adsorption into the mold where it continues theoxidation 10-5 and where it leads to sponginess of the metal. In themold itself, the walls are with a thin layer or film of always coveredetc., adsorbed or condensedv air, moisture, I thereon, and it isFurtherdiflicult to displace this film by the molten metal, such metalgenerally having no real wetting action on the mold walls. In producinga casting, this air, etc., as it is slowly dlsplaced accumulate's toform blowholes, blebs, pits, etc., in the surface of the casting.

In another application, Serial No. 391,67 4, filed Sept. 6 1907, I havedisclosed methods and means of counteracting the difiiculties due toadsorbed air and moisture in the cast metal and the mold, the invention,broadly stated, consisting in pouring the molten metal down through alayer of molten wiping material ofsubstantialdepth, whereby its surfacesare wiped free of entrained or adsorbed air and also of adhering oxids,the heavy molten metal itself passing down through the wiping materialas clean metallic-surfaced metal, the several drops or portions of whichare as ready for mutual -union as drops of clean mercury. For thispurpose and to accomplish this end,the layer of wiping material must bequ through free air in transit. The stated method I regard asparticularly adapted tobrass or bronze and other alloys of coppercomprising zinc or tin,but it may also be used for a variety of othermetallic mixtures containing volatile or oxidizable components. V

The flux or slag used may be one having oxid-dissolving properties, asborax or Waterglass ortheir mixtures, or a high sllica slag, or it maybe substantially neutral toward oxids, like borax or water glassneutralized with soda, since in the described method of operation littlechance for oxidation is afforded. a

In melting or making brass under a cover of flux or slag since there is,if the cover be thick, no exposure of the surface'of the alloy to a freeatmosphere into which zinc vapors can expand, nor any absorption of suchvapors, nor 1s there any opportunity for oxidation, the composition ofthe alloy remains substantially constant. If the flux cover berelatively thin on the other hand, exposure of bare metal and oxidationand evaporation will occur during stirring and mixin The flux covertherefore should be quite deep. In tapping off the molten alloy into adeep body of flux or slag, evaporation and oxidation are similarlyprecluded if the metal be taped from a low point in the mass thereo andsentinto the flux through ite deep. 7 I pre erably 7 determined and aclosed conduit. In this method of operation, thewiping function of theflux or slagj in the mold upon the molten metal itself is not soimportant asin the processof said application Sr. No. 391,674, slncesuch metal does not come into substantial contact with air andcannotentrain it or be oxidized thereby, though the wiping functionremains important as far as the mold walls are concerned; for as, themolten metal accumulates in the mold, the wiping material,

being lighter, rises, progressivelywiping the wiping material has animportant effect on: the strength of the cast metal; for the severalparticles of the cast molten metal being clean, are in good condition tounite one with another during solidification and-produce sound metal.

It is a familiar fact that superheated liquids introduced into vesselshaving walls which are not f chemically clean tend to evolve vapors atlocalized oints or nuclei on said walls, and, simi arly, that liquidscontaining crystalhzable components tend to a localized crystallizationon similar foci or nuclei. In vessels with f chemically clean wallsneither of these segregations takes place. of the presence of a largebody of molten flux or wiping liquid in the molds in the presentinvention is that such flux causes 'the mold walls to become chemicallyclean. In molten brass the vapor tension of the zinc is ve high, thecasting temperature of brass ein very near the boiling point of zinc, anin castinginto the ordinary molds nuclei in the walls 'tend to causeevolution of zinc vapors whereas in castin into molds "having walls keptterlal this phenomenon does not occur and the castings are sound andhomogeneous. Furthermore, since-many of the valuable alloy compositionsare not eutectics but tend to segregation or crystallization of alloysor meta s of different composition from that desired, the absence ofcrystallization-aiding nuclei in the walls in the flux-filled molds ofthe present invention aids-materially in securing sound, homogeneouscastings of such compositions.

. The described method, it will be er- One 'of the valuable features-chemica ly clean by flux or wiping maceived, gives means of producingsoun ingots or castings, free from oxid, blow-holes, sponginess ororosity, from alloys of refi'ecise composition. particularly app 'cableto brass and-other ile ' fused wiping material, or. a solid'la er ofalloys containing the readily volatile and oxidizable metal zinc, it-isalso advantageous for use with bronzes and other alloys containing tin,and for ferrous metals containing such oxidizable components aschromium, aluminum, vanadium, tantalum, titanium, manganese, nickel,cobalt, etc., and for steels containing precise amounts of carbon. Themolten metal being shielded from contact with air, these substances donot burn out.

In the accompanying illustration, I have shown,'more or lessdiagrammatically, certain .typical arrangements of apparatus adapted foruse in the described method.

' In this showing :.-Figure 1 shows a veris pivoted to a lever tendingdownward some distance;

heat ofthe metal cast,

tical section of an ingot casting apparatus;

and Fig. 2 shows a section of a modified, Fig. 8 shows a form of suchapparatus. section of a pouring ladle and of an ingot mold in connectiontherewith, both contaming deep layers of molten flux, as described.

In Flg. 1, 1 designates a crucible or heating chamber, closed by cover2, mounted on a hollow pedestal or support 3, against which plays theflame from-an oil burner 4:.

The crucible and support arecontained in a casing 5, having a steeljacket .6. In the bottom of the crucible is an opening 7 normally closedby stopper 8, carried by rod 9, said rod being protected by anencircling annulus 10 of fireclay or other refractory and indifi'erentcruciblematerial. Therod 11 by which it can be moved up or down, therebypermitting or preventing discharge of molten metal through the openingat" the bottom of the crucible. Within the crucible, as shown, are alayer of brass or other alloy 12, and a layer of fused covering materialor flux 13. Below thecrucible and communicating with the hole in itsbottom, is a conduit 14 ex- In casting an ingot of brass or other alloy,a suitable mold 15, containing a deep layer of such material adapted tobe melted y the is placed below the crucible with this conduit. dippinginto the wiping material in the mold. The mold may be completely filledwith the wiping material if desired. As molten metal enters and thiswiping material'is displaced, the latter flows over edge 16 to anysuitable receptacle. I

' In making an alloy which it is desired to have precise in composition,for example, in making brass, one or more of the ingredients may bemelted in the crucible 1, under cover of the flux orslag 13, and theother ingredient added thereto. For example, in making brass, copper may"be melted in said crucible, under the coating 13, or may beintroducedtherein in molten condition,

and solid or molten through such cover,

' nor will any material amount zinc introduced into the molten copper;or

oreferably, the zinc may be melted in the crucible under cover of theflux coating 13, which prevent-s evaporation and oxidation and maintainsthe metal with a clean surface, and the molten copper poured through theflux or slag 13 into the zinc, or the copper may be poured through suchcover '13 into contact with the zinc while the latter is still solid,the heat of themolten copper melting the zinc but the thick cover 13preventing oxidation of the zinc below such cover and preventingmaterial volatilization of the zinc. In these ways alloys or,mixtures ofvery recise composition may be made, there bemg'practically no escape ofeither metal prior to the min ling of the metals. Or, the brass, alreadyormed,-may be placed in the crucible 1 and melted under cover of thematerial 13, or it may be melted elsewhere and poured through such coverinto the crucible. By whichever of the above described ways the alloy isformed or melted or heated to the desired condition for pouring, it willbe preserved practically free from oxid and will maintain for a longperiod of time practically its original composition. The thick cover offlux or slag 13 permits free stirring, if such be needed, as isfrequently the case, without exposure of metallic surfaces for oxidationor for volat-ilization of volatile components. In the case of moltenbrass, the zinc being at a temperature below its boilingpoint though atone where it has a high vapor tension, cannot form any material amountof Vapor under the thick flux layer, the molten brass in this respectbehaving like very hot water under a thick layer of floating oil. Thebrass therefore remains of substantially constant composition duringthis operation. With a thin flux'coating, stirring exposes bare metaland zinc .flashe's into vapor form therefrom. After the desired castingtemperature is obtained, the rod 9 is raised and the A molten metalallowed to flow down through conduit 14 to a point below the surface ofthe flux layer in the mold. The small amount of air in the short conduitdoes not have any material oxidizing power he entrained, but any oxidwhich may be formed or any air which may be entrained will be removed,

- by the wiping material, and 'a sound, solid ngot formed.

11 the modified apparatus of Fig. 2, the pedestal 3 carrying thecrucible is hollow and the conduit 14 of Fig. 1 is omitted, the mold inuse 'being placed near or against the bottom of the crucible, therebyminimizing the contact of metal with-air.

'In Fig. 3 I show an ordinary ladle 17 containing a body of molten metal18 covered by a deep layer of flux er slag 19; and adjacent to saidladle I show a mold 20 concover 18, and when an alloy of the desiredcomposition has been produced, the molten metal maybe poured into themold. Or the ladle may be filled with molten brass or other alloy fromany suitable source, and then the molten metal poured thence into themold, the contact of the molten metal with the air during pouring beingtoo brief to permit-material oxidation or volatiliza- ,tion. As is wellknown, a relatively heavy liquid may bepoured otffrom beneath arelatively light liquid or. floating mass, with very little, if any,escapeof the lighter subin permanent molds of any of any other specialform.

stance,'hence, as will bereadily understood, it is easy to pour oflthe'ffmolten metal from beneath the layer 19 with practically no loss ofmaterial from said layer. However, ,there is-no objection to the passingof more or less of this material 19 into'the mold, as it merely adds tothe amount of such material inthe mold.

The mold into which the molten alloy is cast may be a mold of specialconfiguration; that is to say, a mold of some machine part, a gearwheel, for example, or of'statuary, or My process lends itselfparticularly to the casting of alloys desired shape.

hat I claim 1s:- y 1 i 1. Inthe production of castings, the processwhich comprises producing a mass of molten metal under a deep layer ofmolten covering material and tapping metal from a point below such layerand flowing it through a deep layer of wiping material into a suitablemold.

2. In the production of castings, the process which comprises producinga molten mass of an alloy containing easily oxidizable or volatilizablecomponents under a deep layer of molten covering material and tappingthe metal from a point below such layer and flowing it through a deeplayer of wiping material into a'suitable mold.

3. In the production of castings, the procwhich comprises producing amolten mass of a metal comprising zinc under a deep layer of moltencovering material and a metal "tapping metal from a point below suchlayer and flowing it through adeep layer oflwiping material into asuitable mold 4;. In the production of castings, the process whichcomprises producing a molten mass of brass under a deep layer of moltencovering material and tapping the molten ess which comprises flowing amolten alloy rom a point below such layer and" flowing it through a deeplayer of fusible through a deep layerof fusible wiping materialcontained in said mold, without substantial contact with air.

6. In the productionof brass castings, the process which comprisesflowing a molten alloy or mixture containing a readily oxidizable orvolatilizable ingredient into a mold through a deep layer of fusiblewiping material contained 1n said mold.

7. A process of formin and casting .alloys of .precise' compositlon,which comprises melting one of the constituents of the alloy under adeep layer of molten covering material and adding the other constituentor constituents thereto while suchfirstconstituent is molten, and thencasting the re-, sulting alloy from beneath such covering material intoa suitable receptacle.

. 8. A process of forming and casting alloys of precise composition,which comprises melting one of .the constituents of the alloy underadeep layer of molten covering material and adding the other constituentorconstituents thereto while such first constituent is molt-en,thoroughly mingling the constituents and then casting the resultingalloy from beneath such covering material into a suitable receptacle.

9. A process of forming and. casting alloys of precise composition,which comprises melting one of theconstituents ofthe alloy under a deeplayer of molten covering material and adding the other constituent orconstituents thereto while such first "constituent is molten andcastingthe alloyso produced through a deeplayer of wiping material into asuitable receptacle.

10'. A process of forming and casting alloys of precise composition,which comprises melting one of the constituents of the alloy under adeep layer of molten covering material and adding the other constituentor -constituents thereto while such first constituent is molten,-thoroughly mingling the constituents and then casting the alloy soproduced through a deep layer of wiping material into a suitablereceptacle.

11. A process of'produoing alloys such as brass, bronze, etc.,containing one or more readily volatilizable constituents which-consistsin melting such volatilizable 'constituout or constituentsunder a deeplayer of molten covering material and thereby reducing loss of suchconstituents, and mixing the so melted metal with the other constituentor constituents of the alloy and then pouring the alloy so produced frombeneath such covering material into a suitable receptacle.

12. A process of producing alloys such as brass, bronze, etc.,containing one or more readily volatilizable constituents which consistsin melting such Volatilizable constituent or constituents under a deeplayer of 130 molten coverifig material 'and thereby reducing'loss ofsuch constituents, and mixing the so melted metal with the otherconstituent or constituents of the alloy and then pouring the alloy soproduced from beneath such covering material through a deep layer ofwiping material into a suitable receptacle.

13. A process of producing brass of pre-' cise composition whichcomprises covering zinc with a deep layer of fusible covering materialand pouring molten copper through such covering material into contactwith the gling zinc and thereby melting the zinc and minit with the coper and then pouring the molten alloy so" produced from beneath saidlayer of covering material into a suitable receptacle.

In testimony whereof I aflix my signature, in the presence of twowitnesses.

JOHN F. MONNOTQ V Witnesses:

H, M. MARBLE, FRANK E. RAFFMAN.

